1. Field of the Invention
The present invention relates to an intravascular catheter having a stiff proximal end portion and gradually softer and more flexible portions progressively toward a distal end of the catheter which is used for diagnostic, interventional and or drug infusion procedures such as blood clot dissolving drugs, chemotherapeutic agents, and injection of contrast media to visualize vasculature and or anatomy using a fluoroscope to assist visualization of the catheter inside the human body. The present intravascular catheter can also be used to deliver coils to aneurisms, and embolic agents to arteriovenous malformation (AVM) in the brain and other parts of the human vasculature such as uterine fibroids. The latter procedure is usually referred to as uterine fibroid embolization (UFE). The present invention more specifically relates to micro catheters for use in interventional neuro radiological procedures where access to brain vasculature is required. Further, the present invention relates to a microcatheter to deploy coils and embolic agents to treat certain brain vasculature syndromes to include but not limited to aneurisms and AVM indications.
2. Description of the Related Art
Intravascular catheters are used to diagnose and treat a number of medical conditions of the vascular system using a technique called angiography. A number of intravascular catheters are used to diagnose coronary artery disease related to stenosis and to determine hemodynamic factors such as cardiac output. In addition, smaller catheters, “micro-catheters”, are used to infuse certain blood clot dissolving drugs to the coronaries or to brain blood vessels in stroke related cases. Further, in addition, intravascular catheters are also used to deploy stents in the coronary arteries as well as in the peripheral vasculature; other indications may include but not limited to deployment of embolic agents and coils to target vasculature within the brain and elsewhere in the human body.
In order to properly navigate or manipulate a catheter after introduction in the human vasculature, it is imperative that the intravascular catheter be designed and constructed in such a manner as to facilitate introduction into a blood vessel and to support further manipulations to reach the target blood vessel. Manipulation of the catheter is done by the physician using the proximal segment of the catheter, after catheter introduction and external to the blood vessel; that is, the catheter needs to be rotated (torque) outside the body in the proximal segment of the catheter and a corresponding rotational reaction must be achieved in the distal tip segment inside the body. Therefore, a vascular catheter, to sustain torsional continuity from the proximal end to the distal end of the, while inside the vasculature, must transmit torque from the proximal end to the distal end inside the body. The typical distance between proximal and distal end for vascular catheters ranges between 80-120 centimeters and shorter for renal applications that require a length of approximately 45-55 centimeters; thus, a vascular catheter is required to advance forward when pushed, be able to be retrieved when pulled and to rotate when torque is applied as part of the maneuvering process to reach the target vessel. Another critical characteristic is that the catheter's wall must not collapse (kink) and retain its lumen integrity, cylindrical shape or ovality during the medical procedure.
Heretofore, a number of analogous and non-analogous intravascular catheter constructions have been proposed, as disclosed in the following U.S. Patents:
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